year, and the period required to double world population had declined to 116 years. By the decade 1930 to 1940, world growth, at 1 percent per year, would have doubled the population in 69 years. At the present rate of growth, 2 percent per year, world population would double in 35_years,. EXPLANATION OF ACCELERATED GROWTH During__the__3_centuries of the...modem.eiaa.jTorn 1650 to 1950, world pnrvjj]atinn niulli£l]edj.bQu^ fivefold, figra_Qj_to 2.5 bjlligrrr0'ge Table 1.) Butoverjthis time span the population of Europe increased almost sixfold; the population of Europe and European descendants combined, about sevenfold- The.-population of northern America (north of the Rio Grande) increased about 168-fold and that of Latin America about 23-fold. During the same period the population of Asia increased less than fourfold in contrast to what may have been a much slower increase before that time. (In absolute numbers the increase was greater than that of all other continents combined.) Numbers in Africa only doubled. It is clear that greatly accelerated growth occurred first among the nations that first experienced modernization, the combination of "revolutions"— the agricultural revolution, the commercial revolution, the industrial revolution, the scientific revolution, and the technological revolution. Explosive population growth, the "vital revolution," did not reach significant proportions among the two thirds of mankind in Asia, Latin America, and Africa until after World War II—less than one human generation ago. The reason for the population explosion is to be found in the interaction of the components of population growth—births (fertility) and deaths (mortality) for the world as a whole, and fertility and mortality and net migration for any subdivision of the world. To explain the population explosion demographers have a theory of the demographic transition. In brief, the explanation lies in the fact that man is the only complex culture-building animal on this globe and in building his culture he has effected great reductions in the death rate well in advance of any corresponding declines in the birth rate. Although research indicates that there have been large regional variations in mortality and fertility changes, the greatly accelerated rate of population growth is the product of natural increase, that is, the excess of births over deaths. Decrease in Death Rate The decrease in the death rate may, in general, be attributed to a number of causes (8): 1. Increased productivity ushered in by the agricultural, commercial, and industrial revolutions resulting in higher levels of living—including better nutrition Viottor lil/itirr A>/-»">/-) i t i nnc or>/4 lioftoi- ViAoltViopment of man.